Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 120315 AFDCTP Area Forecast Discussion National Weather Service State College PA 1115 PM EDT Tue Aug 11 2020 .SYNOPSIS... A weak cold front will pass through Central Pennsylvania tonight and Wednesday before stalling just south of the Maryland border. The front will lead to a daily chance of thunderstorms, mainly across the south, for the rest of the week. Some of the rain could be heavy along and south of the stalled front. A gradual cooling trend will be seen each day through the end of the week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Weak cold front dropping SE across CWA late this evening continues to show little sensible weather for Central PA. Isold coverage of showers and storms will persist along and ahead of the front into the overnight hours where low Pops continue, mainly over the southeast third of central PA. Mins will range from around 60F over the northwest to the lower 70s southeast. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Over the NW behind the front on Wednesday, the sensible change will be felt as dewpoints drop back into the low to mid 50s. Lack of moisture and flat flow/weak forcing keeps POPs low to the NW, but proximity to stalling boundary along and south of the Mason Dixon line ramps POPs up to likelies and near categorical for portions of the Lower Susq. Deep moisture pools to over 2.0" PW just south of the Mason Dixon line, and areas just outside of our CWA that were hit hardest by Isaias`s rains will be prone to flash flooding. Day 2 Excessive Rainfall Outlook from WPC has slid slight/marginal risk a bit further northward into the Lower Susq, so as this slides into Day 1 we will take a renewed look at need for a Flood Watch for York/Lancaster counties. Maxes on Wed will be only 1-2F cooler than Tues. The high dewpoints in the SE will continue, so the heat index there will once again peak in the m90s. Otherwise, a more comfortable day is in store for most of the area. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... The extended forecast will be dominated by a broad upper level trough and a very slow-moving, relatively weak surface cold front. The front should be at or south of the Turnpike by Thursday, and linger there for several days. High pressure from Canada should help keep the front south of the Mason-Dixon line through much of the weekend. As such, afternoon showers and storms should be restricted to the southern tier, at least through Friday. The ECENS and GEFS both keep the northern two- thirds of the Commonwealth dry through Saturday morning, with diverging solutions after that. Very weak low pressure should develop over Kentucky late week and drift across the DelMarVA, bringing potential for a couple more concentrated moisture surges this weekend to southern PA. The 12Z GFS brings precipitation all the way into southern New York by Saturday, with upwards of an inch of QPF by Saturday evening for much of the area. Nonetheless, the GEFS, ECENS, and 00Z EURO keep precipitation restricted to the southern tier all the way through the weekend. Owing to weak forcing, a rapidly developing high in Canada, and a persistent period of dry weather across most of Central PA, have gone with the drier solutions and thrown out any consideration of the 12Z GFS. Of additional significance is the trend of cooler temperatures each successive day all the way through the weekend. 24-hour max T trends will be 0 to -5 degrees each afternoon as persistent cloud cover and daily rain chances will help push temperatures to near or below normal by the weekend, before a gradual rebound to warmer temps again next week. The best chance of rain for the northern tier in the extended forecast arrives early next week as a cold front will surge southeastward. Behind it, strong high pressure will keep near- to-below normal temperatures in place. The Climate Prediction Center 6-10 and 8-14 day temperature outlooks place central PA in the "equal chances" category, which is a welcome change from what has been a consistent stretch of above normal temperatures. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Convection just about done across the region this evening. Will see some locally reduced vsby with ground fog overnight. Weak frontal boundary will drift SE overnight across the region and be the focus of more convection on Tuesday across the southern half of PA. Most of the region will be VFR/MVFR outside of any convection across the south. This unsettled pattern will continue across this area for the next several days mainly during the afternoon hours. Outlook... Wed-Sat...Isold-sct t-storms possible mainly srn 1/2. && .CLIMATE... A daily record high temperature of 86 degrees was set at Bradford yesterday (8/10). The previous record high was 85 degrees set back in 1975. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/RXR NEAR TERM...DeVoir/RXR SHORT TERM...DeVoir LONG TERM...RXR/Banghoff AVIATION...Ross CLIMATE...

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